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A025028 Least non-residue mod n is 23. 0
10559, 15791, 21118, 31582, 50951, 53231, 53881, 88079, 88919, 92569, 97919, 101902, 102001, 106462, 107762, 123191, 128519, 130729, 138311, 142271, 144169, 158759, 166319, 166609, 167879, 173209, 174599, 176158, 176401, 177838, 185138 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..31.

PROG

(PARI) residue(n, m)=local(r); r=0; for(i=1, floor(m/2), if(i^2%m==n, r=1)); r

isA025028(n)=local(a); a=1; forprime(p=2, 19, a=a && residue(p, n)); a=a && !residue(23, n); a \\ Michael B. Porter, Apr 30 2010

(PARI) is(n)=forprime(p=2, 23, if(!issquare(Mod(p, n)), return(p==23))); 0 \\ Charles R Greathouse IV, Jan 24 2020

CROSSREFS

Sequence in context: A065319 A063060 A187727 * A063063 A183600 A302772

Adjacent sequences:  A025025 A025026 A025027 * A025029 A025030 A025031

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified April 1 10:33 EDT 2020. Contains 333159 sequences. (Running on oeis4.)